Due to an ongoing increase in the number of clinical analyses needed in medical diagnostics, there continues to be a strong demand for the automated analysis of body fluids. In recent years, many efforts have been made to develop new microfluidic devices for the automated centrifugal force based analysis of liquid samples which have minute volumes, e.g. as low as micro-liters, in order to lower sample consumption, hasten analysis times and increase sample throughput.
In the technique of using centrifugal force to drive fluids, the microfluidic device is spun around a spin axis so that samples that are placed at an inner position relative to the spin axis can be transported to an outer position by centrifugal force created as the device rotates. By using centrifugal force for the transport of fluids, sophisticated and expensive mechanical pumps for generating positive or negative pressures acting on the fluids can be avoided.
In general, microfluidic devices for the centrifugal force based analysis of liquid samples include one or more microfluidic structures provided with various functional areas, such as flow channels and reaction chambers. In such microfluidic devices, the reaction chambers typically have greater cross-sectional dimensions than those of the flow channels, and are used for the reaction of samples with one or more reagents to obtain reaction products enabling analysis of substances such as, e.g. nucleic acids, contained therein.